One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,6,5)(3,8,4,7)(9,10,13,15)(11,17,19,14)(12,16,21,23)(18,24,20,22)(25,26,32,29)(27,31,34,36)(28,33,39,30)(35,37,38,40)(1,3,6,4)(2,7,5,8)(9,11)(10,14)(12,20)(13,19)(15,17)(16,24)(18,21)(22,23)(25,27)(26,31)(28,38)(29,36)(30,37)(32,34)(33,40)(35,39)(10,15)(14,17)(16,23)(22,24)(25,28,32,39)(26,33,29,30)(27,35,34,38)(31,37,36,40)(1,3,6,4)(2,7,5,8)(9,10)(11,14)(12,16)(13,15)(17,19)(18,22)(20,24)(21,23)(25,29,32,26)(27,36,34,31)(28,30,39,33)(35,40,38,37)(1,4,6,3)(2,7,5,8)(9,12,13,21)(10,16,15,23)(11,18,19,20)(14,22,17,24)(25,30)(26,28)(27,37)(29,39)(31,38)(32,33)(34,40)(35,36)(1,5,6,2)(3,8,4,7)(9,11)(10,14)(12,20)(13,19)(15,17)(16,24)(18,21)(22,23)(25,31,32,36)(26,34,29,27)(28,37,39,40)(30,35,33,38)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.